The lowest level I would recommend taming is a 90.they have a good weight and damage, and it doesn't take long for its health to get to 20,000. Then, if you want, you can usually get it's damage to about 300%
Tranq Arrows/Darts DO NOT WORK!!! To knock this out you need to use a catapult and shoot in only on it's back. If you shoot it on it's legs it will kill it. UP-VOTE SO EVERYONE KNOWS & TO GET DODODEX TO ADD THIS!!!